`d3fc`/`datagrid` packages point to nonexistent "types" location

[brianblakely]

https://github.com/finos/perspective/blob/00137e3eeb861d9c3640fbc0a6660573c6e11f69/packages/perspective-viewer-d3fc/package.json#L34

The types property above points to a declaration file which is not created. I would file a simple PR to change, but there are two extant D files, "index.d.ts" and "types.d.ts" and I am not sure which is preferable.

[texodus]

Please use the Issue template! I am not a TypeScript expert and we have working TypeScript examples in the repo.

I spent some time experimenting with this and I've found two cases that create warning in a no-config TS project:

1. Trying to capture the export symbol e.g. import * as dg from "@finos/perspective-viewer-datagrid". This is bugged as you describe - but there are no exports in these packages so you should be able to work around this by removing the dg binding.
2. Importing a sub-path file directly e.g. import "@finos/perspective-viewer-datagrid/dist/esm/perspective-viewer-datagrid.js".

I have updated the types exports for these packages in #2910, this will only impact #1 (but you should likely not bind this symbol anyway ..). If there are additional failures, please create a new Issue with details.